Apparatus for testing infrared camera

ABSTRACT

An apparatus for testing infrared cameras includes: a front plate which has holes arranged in line, and which is adapted to emit an amount of infrared light; and a back plate which is disposed in parallel to and behind the front plate as viewed from infrared cameras to be tested, and which is adapted to emit a different amount of infrared light when compared with the front plate. The back plate is disposed at lower portions of pillars. On the other hand, the front plate is made vertically movable in front of the back plate and along the pillars. By being controlled by a controller, the front plate is movable from the ground height to a level corresponding to approximately two times the height of the back plate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an apparatus for testinginfrared cameras, which are installed on a vehicle, for measuringdistances to objects.

[0003] Priority is claimed on Japanese Patent Application No.2002-290234, filed Oct. 2, 2002, the content of which is incorporatedherein by reference.

[0004] 2. Description of Related Art

[0005] A three-dimensional measuring method has been known in the art inwhich a distance to an object is determined using parallax between apair of object images taken by a pair of cameras (stereo cameras). Insuch a method, an apparatus for correcting images must be used in orderto accurately measure a distance to an object by correcting shift ofimages due to distortions of lenses and variations in focal lengthsthereof. In an example of such an apparatus, a specific image pattern,such as a regular grid pattern, for measuring an amount of correction issimultaneously taken in advance using both stereo cameras, and theamounts of corrections in the coordinates are calculated pixel by pixelwith regard to each image taken by each of the cameras. The calculatedresults are stored as a correction table for the coordinates, and thedata stored in an image memory are corrected pixel by pixel using thecorrection table for the coordinates so that accurate image data areobtained. In a method disclosed in, for example, Japanese UnexaminedPatent Application, First Publication No. Hei 11-325889, the correctionsin shifting of images due to distortions of lenses and variations infocal lengths thereof are executed only in the vertical direction.

[0006] As an example to which the above-mentioned three-dimensionalmeasuring method using stereo cameras is applied, a system is knownwhich detects obstacles in front of a vehicle earlier than the driver ofthe vehicle does, and which notifies the driver of the existence of theobstacles. In this case, in general, infrared cameras, which enabletaking infrared images, are used as the stereo cameras, in order to aiddriving under poor visibility conditions.

[0007] As mentioned above, in order to correct shifting of images due todistortions of lenses and variations in focal lengths thereof, aspecific image pattern, such as a regular grid pattern, for measuring anamount of correction is simultaneously taken in advance using bothstereo cameras, and the amounts of corrections in the coordinates arecalculated pixel by pixel with regard to each image taken by each of thecameras; however, in the case of infrared cameras used for the stereocameras, a problem is encountered in that it is difficult to form aregular grid pattern which can be accurately taken by the infraredcameras.

SUMMARY OF THE INVENTION

[0008] In view of the above circumstances, an object of the presentinvention is to provide an apparatus for testing infrared cameras, whichenables an easy measurement of errors in projected coordinates ofobjects in both the horizontal direction and vertical direction.

[0009] In order to achieve the above object, the present inventionprovides an apparatus for testing infrared cameras including: a coverplate which has holes arranged in line, and which is adapted to emit anamount of infrared light; and an emission source which is disposed inparallel to and behind the cover plate as viewed from infrared camerasto be tested, and which is adapted to emit a different amount ofinfrared light when compared with the cover plate.

[0010] According to the apparatus for testing infrared camerasconfigured as described above, by disposing the emission source inparallel to and behind the cover plate which has holes arranged in line,and by making the emission source emit infrared light having anintensity which is greater than that of the infrared light emitted fromthe cover plate, infrared light emitting portions aligned in line can beformed using the infrared light passing through the holes formed in thecover plate. On the other hand, by making the emission source emitinfrared light having an intensity which is less than that of theinfrared light emitted from the cover plate, infrared light non-emittingportions aligned in line can be formed due to differences between theintensity of the infrared light emitted from the emission source and theintensity of the infrared light emitted from a portion of the coverplate other than the holes.

[0011] In the apparatus for testing infrared cameras, the emissionsource may include a metal plate, and a heat source which is connectedto the metal plate.

[0012] According to the apparatus for testing infrared camerasconfigured as described above, infrared light can be uniformly emittedfrom the metal plate by heating the metal plate using the heat source,or by cooling the metal plate using the heat source. By making theuniformly emitted infrared light pass through the holes formed in thecover plate, the infrared light emitting portions which are accuratelyaligned or the infrared light non-emitting portions which are accuratelyaligned can be easily formed due to difference between the intensity ofthe infrared light emitted from the emission source and the intensity ofthe infrared light emitted from the cover plate.

[0013] In the apparatus for testing infrared cameras, the emissionsource may comprises a metal plate, and an element which is adhered tothe metal plate, and which has an infrared emissivity that is higherthan that of the cover plate.

[0014] According to the apparatus for testing infrared camerasconfigured as described above, because the element having an infraredemissivity that is higher than that of the cover plate is adhered to themetal plate, the infrared light emitting portions which are accuratelyaligned can be formed at low cost by making the element uniformly emitinfrared light, and by making the infrared light pass through the holesformed in the cover plate.

[0015] In the apparatus for testing infrared cameras, the cover platemay have been subjected to a processing for reducing infrared lightreflection.

[0016] According to the apparatus for testing infrared camerasconfigured as described above, because the cover plate has beensubjected to a processing for reducing infrared light reflection, theinfrared light emitted from the emission source can be prevented frombeing reflected by a vehicle on which the infrared cameras to be testedare installed, and also, reflected infrared light can be prevented frombeing reflected by the cover plate.

[0017] In the apparatus for testing infrared cameras, the cover platemay be vertically movable in front of the emission source as viewed fromthe infrared cameras to be tested from a first position at which testingof the infrared cameras is executed to a second position which is higherthan the first position. The second position may be preferably set to besufficiently higher than the first position so that the cover plate isnot heated by a heat source of the emission source.

[0018] According to the apparatus for testing infrared camerasconfigured as described above, the vertical level of the cover plate canbe adjusted in accordance with the vertical levels of the infraredcameras to be tested even when the vertical levels of the infraredcameras are changed. In addition, by moving the cover plate from aposition in front of the emission source so as to make the distancebetween the cover plate and the emission source greater, the cover plateis prevented from being heated unnecessarily, which leads to emission ofunnecessary infrared light, or the cover plate is prevented from beingcooled unnecessarily, which leads to non-emission of necessary infraredlight.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a perspective view showing an embodiment of an apparatusfor testing infrared cameras according to the present invention.

[0020]FIG. 2 is a plan view showing a target portion of the apparatusfor testing infrared cameras according to the above embodiment.

[0021]FIG. 3 is a front view showing the target portion of the apparatusfor testing infrared cameras according to the above embodiment.

[0022]FIG. 4 is a diagram showing a grayscale image of the targetportion of the apparatus for testing infrared cameras according to theabove embodiment taken by infrared cameras installed on a vehicle.

[0023]FIG. 5 is a diagram showing a binarized image obtained by applyinga binarization process to the grayscale image of the target portion.

[0024]FIG. 6 is a flowchart showing a process for testing infraredcameras, in which the apparatus for testing infrared cameras accordingto the above embodiment and an image processing unit installed in thevehicle are used.

[0025]FIG. 7 is a diagram showing a property curve of error incoordinates projected onto an image plane, which was obtained using theapparatus for testing infrared cameras according to the aboveembodiment.

[0026]FIG. 8A is a schematic diagram illustrating the relationshipbetween a distance R from the center of a lens to an object and thecoordinates of the geometric center of the object, and FIG. 8B is adiagram showing the property curve of error in coordinates projectedonto an image plane, which was obtained using the apparatus for testinginfrared cameras according to the above embodiment, as a property curveof error in coordinates with respect to the distance R.

[0027]FIG. 9 is a schematic diagram illustrating mounting angle (panningangle θ) of an infrared camera installed on a vehicle.

[0028]FIG. 10 is a diagram showing a grayscale image of the targetportion of the apparatus for testing infrared cameras according to theabove embodiment taken by the infrared cameras installed on the vehicle.

[0029]FIG. 11 is a diagram showing another property curve of error incoordinates projected onto an image plane, which was obtained using theapparatus for testing infrared cameras according to the above embodimentin an alternative process.

DETAILED DESCRIPTION OF THE INVENTION

[0030] An embodiment of the present invention will be explained belowwith reference to appended drawings.

[0031]FIG. 1 is a perspective view showing an embodiment of an apparatusfor testing infrared cameras according to the present invention, whichis to be installed in a manufacturing line in a plant. FIG. 2 is a planview showing a target portion of the apparatus for testing infraredcameras according to the present embodiment. FIG. 3 is a front viewshowing the target portion of the apparatus for testing infraredcameras.

[0032] As shown in FIG. 1, the apparatus for testing infrared camerasaccording to the present embodiment includes a back plate 2 and a frontplate 3 which together form a target portion that is disposed in frontof a vehicle 1 which is provided with infrared cameras to be tested atthe front end thereof. The back plate 2 of an aluminum plate is acts asan infrared light emission source when the entirety thereof is heated orcooled. The front plate 3 of an aluminum plate is disposed closer to thevehicle 1 than from the back plate 2. Circular holes (hereinafterreferred to as target holes) having the same size with respect to eachother are formed in the front plate 3 at a regular interval.

[0033] The back plate 2 is a plate-shaped element whose width in thehorizontal direction is approximately the same as that of the vehicle 1,and whose height in the vertical direction is sufficiently large whencompared with the vehicle 1 regardless of models of the vehicle 1 sothat testing of the infrared cameras is allowed wherever the infraredcameras are installed on the vehicle 1. The back plate 2 is disposed atlower portions of pillars 4 a and 4 b. On the other hand, the frontplate 3 is made vertically movable in front of the back plate 2 andalong the pillars 4 a and 4 b. By being controlled by the controller 5,the front plate 3 is movable from the ground height to a levelcorresponding to approximately two times the height of the back plate 2.Accordingly, the vertical level of the target portion including the backplate 2 and the front plate 3 can be adjusted to a level of the infraredcameras even when the level of the infrared cameras are changeddepending on the models of the vehicle 1.

[0034] The back plate 2 and the front plate 3 will be further explainedbelow in detail. As shown in FIG. 2, the back plate 2 is provided withtemperature adjusting devices 6 such as heaters or Peltier elements onthe backside thereof as viewed from the vehicle 1 in order to executeheating or cooling of the entirety of the back plate 2.

[0035] The direct transmission of heat from the back plate 2 to thefront plate 3 is prevented by supporting the front plate 3 by thepillars 4 a and 4 b so that the front plate 3 is separated from the backplate 2 by an appropriate distance, and by fabricating the pillars 4 aand 4 b with a material having low thermal conductivity. When the frontplate 3 is moved to the uppermost portions of the pillars 4 a and 4 b,the front plate 3 is not affected by heating and cooling of the backplate 2.

[0036] As shown in FIG. 3, the front plate 3 has the circular targetholes (eleven target holes H1 to H11 in this embodiment) which arearranged in line in the horizontal direction along the center line ofthe front plate 3 at a regular interval; therefore, the back plate 2 canbe seen from the vehicle 1 through the target holes H1 to H11. Inaddition, raised paper 3 a having low reflectance is adhered to thefront face (front surface) of the front plate 3 as viewed from thevehicle so that the infrared light reflected by the vehicle 1 or emittedfrom the vehicle 1 will not be reflected by the front plate 3 and willnot return to the vehicle 1.

[0037] In the target portion as configured above, the back plate 2 andthe front plate 3 are overlaid each other, and the back plate 2 isheated. The infrared light emitted from the back plate 2 is taken by theinfrared cameras installed on the vehicle 1 through the target holes H1to H11 formed in the front plate 3 to obtain a grayscale image shown inFIG. 4. A binarization process is applied to the grayscale image shownin FIG. 4 to obtain a binarized image shown in FIG. 5.

[0038] In contrast, when the back plate 2 is cooled, the infrared lightemitted from the front plate is take by the infrared cameras; therefore,another binarized image is obtained which is reversed in white and blackwhen compared with the binarized image shown in FIG. 4.

[0039] In a state in which the back plate 2 is heated to make the backplate 2 emit infrared light, infrared light having higher intensity canbe obtained by adhering a material having an infrared reflectancegreater than 0.9 such as paper or carbon to the back plate 2.Accordingly, when infrared light having higher intensity is desired, theback plate 2 is heated using the temperature adjusting devices 6 inaddition to adhering paper or carbon to the back plate 2. When low costis desired for the apparatus for testing infrared cameras, thetemperature adjusting devices 6 may be omitted, and just the back plate2 having paper or carbon thereon may be used as the infrared lightemission source.

[0040] Next, a verification process for the on-vehicle infrared camerasusing the apparatus for testing infrared cameras of the presentembodiment will be explained below.

[0041]FIG. 6 is a flowchart showing the verification process for theinfrared cameras, in which the apparatus for testing infrared camerasaccording to the above embodiment and an image processing unit installedin the vehicle 1 are used.

[0042] In FIG. 6, the image processing unit obtains infrared images asan output signal of the stereo infrared cameras (step S1), executes anA/D conversion (step S2), and stores grayscale images in an image memory(step S3). A right image of the target holes H1 to H11 is obtained by aright infrared camera, and a left image of the target holes H1 to H11 isobtained by a left infrared camera.

[0043] In step S3, the grayscale images such as shown in FIG. 4 isobtained, and then a binarization process is applied to each of theright and left images to obtain the binarized images such as shown inFIG. 5 (step S4). In the binarization process, regions in the image thatare brighter than a brightness threshold ITH are deemed as “1” (i.e.,white), and regions in the image that are darker than the brightnessthreshold ITH are deemed as “0” (i.e., black).

[0044] Next, the geometric center of each of the target holes H1 to H11in the binarized image is calculated (step S5).

[0045] Next, an error in projected coordinates are calculated (step S6)based on the differences between the theoretical projected X coordinatesand the observed X coordinates of the geometric centers obtained in stepS5. More specifically, the coordinates of the target holes H1 to H11 inactual space projected onto the image (the theoretical projected Xcoordinates) are obtained using Equation (1) shown below. The errors inprojected X coordinates are obtained by subtracting the observed Xcoordinates of the geometric centers from the theoretical projected Xcoordinates.

x=(F·X)/(p·Z)  Equation (1)

[0046] In Equation (1), “x” indicates the coordinate of the target holeprojected onto the image, “X” indicates position of the target hole inthe actual space shown in FIG. 4, “Z” indicates the distance between thetarget hole in the actual space and the camera, “p” indicates pitch ofpixels, and “F” indicates the focal length of the lens of the camera.

[0047] Moreover, with regard to each position of the binarized targetholes H1 to H11 shown in FIG. 5, an error in projected X coordinate iscalculated, and then a property curve of error in coordinates projectedonto the image plane for the errors in projected X coordinates of thetarget holes H1 to H11 is obtained with regard to each of the right andleft images (step S7). More specifically, as shown in FIG. 7, theproperty curve of error in the coordinates projected onto the imageplane, which corresponds to the errors in projected X coordinates of thetarget holes H1 to H11, is drawn by plotting points in such a mannerthat the observed X coordinates of the geometric centers are measuredalong the x-axis, and the errors in projected X coordinates are measuredalong the y-axis, and by curve-fitting the plotted points using a lineor using a polynomial approximation. Equation (2) shown below is appliedto a six-degree polynomial approximation for the property curve of errorin the coordinates projected onto the image plane as shown in FIG. 7.The “α” shown in FIG. 7, for example, indicates the error in theprojected coordinate of the target hole H9.

y=a·x ⁶ +b·x ⁵ +c·x ⁴ +d·x ³ +e·x ² +f·x+g  Equation (2)

[0048] The obtained property curve of error in the coordinates projectedonto the image plane is stored as a camera coordinates correctionparameter (step S8).

[0049] The property curve of error in the coordinates projected onto theimage plane shown in FIG. 7 indicates the errors in the projected Xcoordinate with respect to the observed X coordinates of the geometriccenters of the objects (target holes); however, another property curveof error in the coordinates projected onto the image plane, whichindicates the errors in the projected coordinate with respect to thedistance from the center of the lens of the camera, may be drawn andused because distortion in a lens is, in general, symmetrical about thecenter of the lens. More specifically, when the observed coordinates ofthe geometric center of an object is expressed by “(Xp, Yp)” as shown inFIG. 8A, and the distances R from the center of the lens calculatedusing Equation (3) are measured along the x-axis instead of the observedX coordinates of the geometric centers in the case of FIG. 7, the errorsin the projected coordinate with respect to the distances R from thecenter of the lens are indicated as shown in FIG. 8B.

R=(Xp ² +Yp ²)^(1/2)  Equation (3)

[0050] In the above method for obtaining the property curve of error inthe coordinates projected onto the image plane based on the differencesbetween the theoretical projected X coordinates and the observed Xcoordinates of the geometric centers, the position and angle of thecamera must be adjusted so that the center target hole H6, which is tobe the basis of measurement, is positioned at the center of the image inorder to use Equation (1); however, it is difficult to accurately adjustthe position and angle of the camera due to limitations in accuracy ofinstallation of the cameras at a factory, due to limitations in accuracyof equipment in the factory.

[0051] However, even when the position and angle of the camera are notadjusted, the theoretical projected coordinates can be calculated if aninstallation angle (i.e., a panning angle) θ of the camera, which isillustrated in FIG. 9, can be found. In this case, the coordinatesprojected onto the image plane (i.e., the theoretical projected Xcoordinates) of the target holes H1 to H11 are calculated based on thepositions of the target holes H1 to H11 in the actual space usingEquation (4).

X={F(X·cos θ+Z·sin θ)}/{p·(−X·sin θ+Z·cos θ)}  Equation (4)

[0052] In Equation (4), “x” indicates the coordinate of the target holeprojected onto the image, “X” indicates position of the target hole inthe actual space shown in FIG. 4, “Z” indicates the distance between thetarget hole in the actual space and the camera, “p” indicates pitch ofpixels, “F” indicates the focal length of the lens of the camera, and“θ” indicates the panning angle of the camera.

[0053] Next, another method for obtaining the property curve of error inthe coordinates projected onto the image plane using the apparatus fortesting infrared cameras according to the present embodiment will beexplained.

[0054] In another method for obtaining the property curve of error inthe coordinates projected onto the image plane, the property curve oferror in the coordinates projected onto the image plane is obtainedbased on the differences between the observed distances and thetheoretical distances from the center target hole H6, as the basis ofmeasurement, to the other target holes.

[0055] More specifically, in step S3 shown in FIG. 6, grayscale imagesare obtained, and then a binarization process is applied to each of theright and left images to obtain the binarized images. In thebinarization process, regions in the image that are brighter than abrightness threshold ITH are deemed as “1” (i.e., white), and regions inthe image that are darker than the brightness threshold ITH are deemedas “0” (i.e., black).

[0056] Next, the geometric center of each of the target holes H1 to H11in the binarized image is calculated.

[0057] As shown in FIG. 10, the distances on the image from the centertarget hole H6 to the other target holes (i.e., theoretical distancesLR1 to LR11) are calculated using Equation (5). Next, the errors inprojected X coordinates (the errors in projected X coordinates=theobserved distances from the center target hole H6 to the other targetholes−the theoretical distances from the center target hole H6 to theother target holes) are obtained based on the observed distances fromthe center target hole H6 to the other target holes (LJ1 to LJ11) andthe theoretical distances from the center target hole H6 to the othertarget holes (LR1 to LR11).

1=(F·L)/(p·Z)  Equation (5)

[0058] In Equation (5), “1” indicates the distances on the image fromthe center target hole H6 to the other target holes, “L” indicates thedistances in the actual space from the center target hole H6 to theother target holes as shown in FIG. 10, “Z” indicates the distances inthe actual space from the target holes to the camera, “p” indicatespitch of pixels, and “F” indicates the focal length of the lens of thecamera.

[0059] Moreover, with regard to each position of the binarized targetholes H1 to H11 shown in FIG. 5, the error in the projected X coordinateis calculated as shown in TABLE 1, and then a property curve of error inthe coordinates projected onto the image plane is obtained based on theerrors in the projected X coordinates of the target holes H1 to H11.More specifically, as shown in FIG. 11, the property curve of error inthe coordinates projected onto the image plane, which corresponds to theerrors in projected X coordinates of the target holes H1 to H11, isdrawn by plotting points in such a manner that the observed Xcoordinates of the geometric centers (i.e., the observed distances fromthe target hole H6 and to the other target holes) are measured along thex-axis, and the errors in projected X coordinates are measured along they-axis, and by curve-fitting the plotted points using a line or using apolynomial approximation. Equation (2) shown below is applied to asix-degree polynomial approximation for the property curve of error inthe coordinates projected onto the image plane as shown in FIG. 11. The“β” shown in FIG. 11, for example, indicates the error in the projectedX coordinate (i.e., (LJ9-LR9)) corresponding to the distance from thecenter target hole H6 to the target hole H9. TABLE 1 Observed distanceTheoretical distance from H6 to each of from H6 to each of Error in thethe other target the other target projected X Target hole holes holescoordinate H1 LJ1 LR1 LJ1-LR1 H2 LJ2 LR2 LJ2-LR2 H3 LJ3 LR3 LJ3-LR3 H4LJ4 LR4 LJ4-LR4 H5 LJ5 LR5 LJ5-LR5 H6 — — — H7 LJ7 LR7 LJ7-LR7 H8 LJ8LR8 LJ8-LR8 H9 LJ9 LR9 LJ9-LR9 H10 LJ10 LR10 LJ10-LR10 H11 LJ11 LR11LJ11-LR11

[0060] In the method for obtaining the property curve of error in thecoordinates projected onto the image plane based on the differencesbetween the observed distances and the theoretical distances from thecenter target hole H6, as the basis of measurement, to the other targetholes, even when there is a panning angle θ of the cameras, the propertycurve of error in the coordinates projected onto the image plane can beaccurately obtained based on the differences between the observeddistances and the theoretical distances from the center target hole H6to the other target holes because the distances from the center targethole H6 to the other target holes will not change with the panning angleθ.

[0061] As explained above, the apparatus for testing infrared camerasaccording to the present embodiment includes the front plate 3 havingthe holes arranged in line, and the back plate 2, as the infrared lightemission source, disposed behind the front plate 3 while being inparallel with the front plate 3. In the apparatus for testing infraredcameras, by heating the back plate 2 using the temperature adjustingdevice 6 so that the back plate 2 emits infrared light having anintensity which is greater than that of the infrared light emitted fromthe front plate 3, the infrared light emitting portions aligned in linecan be formed using the infrared light passing through the holes formedin the front plate 3. In contrast, when the back plate 2 is cooled usingthe temperature adjusting device 6, because the front plate 3 emitsinfrared light having an intensity which is greater than that of theinfrared light emitted from the back plate 2, white and black in theimage taken by the infrared camera are reversed.

[0062] Moreover, if the front plate 3 has been subjected to a processingfor reducing infrared light reflection, the infrared light, which isemitted from the back plate 2, and is then reflected by the vehicle 1 onwhich the infrared cameras to be tested are installed, can be preventedfrom being reflected by the front plate 3, and thus effects of thereflected infrared light in the test of the infrared cameras can beeliminated.

[0063] Furthermore, by adhering an element having a high infraredemissivity such as paper or carbon to the back plate 2 so that theelement emits infrared light having an intensity which is greater thanthat of the infrared light emitted from the front plate 3, the cost ofthe apparatus for testing infrared cameras can be reduced because thetemperature adjusting device 6 for heating the back plate 2 may beomitted.

[0064] In addition, by making the front plate 3 vertically movable infront of the back plate 2, the vertical level of the front plate 3 canbe adjusted in accordance with the vertical levels of the infraredcameras even when the vertical levels of the infrared cameras arechanged due to change in the model of the vehicle 1. Moreover, by movingthe front plate 3 from a position in front of the back plate 2 so as tomake the distance between the front plate 3 and the back plate 2, thefront plate 3 is prevented from being heated unnecessarily, which leadsto emission of unnecessary infrared light, or the front plate 3 isprevented from being cooled unnecessarily, which leads to non-emissionof necessary infrared light.

[0065] Accordingly, the distortions of the lenses in various directionsand variations in the focal lengths of the lenses used in the infraredcameras to be tested can be confirmed as the property curve of error inthe coordinates projected onto the image plane by taking the images ofthe infrared emitting portions uniformly formed using the apparatus fortesting infrared cameras, and by comparing the positions of the infraredemitting portions in the actual space with the coordinates of theinfrared emitting portions projected onto the image plane.

[0066] Advantageous Effects of the Invention

[0067] As explained above, according to the apparatus for testinginfrared cameras of the present invention, by disposing the emissionsource in parallel to and behind the cover plate which has holesarranged in line, and by making the emission source emit infrared lighthaving an intensity which is greater than that of the infrared lightemitted from the cover plate, infrared light emitting portions alignedin line can be formed using the infrared light passing through the holesformed in the cover plate. On the other hand, by making the emissionsource emit infrared light having an intensity which is less than thatof the infrared light emitted from the cover plate, infrared lightnon-emitting portions aligned in line can be formed due to differencebetween the intensity of the infrared light emitted from the emissionsource and the intensity of the infrared light emitted from a portion ofthe cover plate other than the holes.

[0068] Therefore, the testing of the infrared cameras can be accuratelyperformed using the infrared light emitting portions which are clearlydelimited, or using the infrared light non-emitting portions which aretaken by the infrared cameras as a reversed pattern when compared withthe infrared light emitting portions.

[0069] According to another apparatus for testing infrared cameras ofthe present invention, the infrared light emitting portions which areaccurately aligned or the infrared light non-emitting portions which areaccurately aligned can be easily formed by heating the metal plate usingthe heat source, or by cooling the metal plate using the heat source sothat infrared light is uniformly emitted from the metal plate.

[0070] Therefore, by controlling the heat source, the contrast in theimage of the emission source taken by the infrared cameras can beincreased, and the testing of the infrared cameras can be accuratelyperformed.

[0071] According to another apparatus for testing infrared cameras ofthe present invention, because the element having an infrared emissivitythat is higher than that of the cover plate is adhered to the metalplate, the infrared light emitting portions which are accurately alignedcan be formed at low cost by making the element uniformly emit infraredlight.

[0072] Therefore, the cost of the apparatus for testing infrared camerascan be reduced.

[0073] According to another apparatus for testing infrared cameras ofthe present invention, because the cover plate has been subjected to aprocessing for reducing infrared light reflection, the infrared lightemitted from the emission source can be prevented from being reflectedby a vehicle on which the infrared cameras to be tested are installed,and also reflected infrared light can be prevented from being reflectedby the cover plate.

[0074] Therefore, distortions in the infrared light emitting portions orin the infrared light non-emitting portions due to the infrared lightreflected by the vehicle and reflected by the cover plate can beprevented, and the testing of the infrared cameras can be accuratelyperformed.

[0075] According to another apparatus for testing infrared cameras ofthe present invention, the vertical level of the cover plate can beadjusted in accordance with the vertical levels of the infrared camerasto be tested. In addition, by moving the cover plate from a position infront of the emission source, the cover plate is prevented from beingheated unnecessarily, which leads to emission of unnecessary infraredlight, or the cover plate is prevented from being cooled unnecessarily,which leads to non-emission of necessary infrared light.

[0076] Therefore, in a manufacturing line of automobiles, for example,the vertical level of the cover plate can be adjusted to the level ofthe infrared cameras to be tested depending on the models of thevehicle. The cover plate is disposed in front of the emission sourceonly when the cover plate is required in the testing of the infraredcameras which is not continuously performed so that the infrared lightemitting portions which are accurately aligned or the infrared lightnon-emitting portions which are accurately aligned are formed, and thusthe testing of the infrared cameras can be accurately performed at anytime.

[0077] While preferred embodiments of the invention have been describedand illustrated above, it should be understood that these are exemplaryof the invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

What is claimed is:
 1. An apparatus for testing infrared cameras,comprising: a cover plate which has holes arranged in line, and which isadapted to emit an amount of infrared light; and an emission sourcewhich is disposed in parallel to and behind the cover plate as viewedfrom infrared cameras to be tested, and which is adapted to emit adifferent amount of infrared light when compared with the cover plate.2. An apparatus for testing infrared cameras, according to claim 1,wherein the emission source comprises a metal plate, and a heat sourcewhich is connected to the metal plate.
 3. An apparatus for testinginfrared cameras according to claim 1, wherein the emission sourcecomprises a metal plate, and an element which is adhered to the metalplate, and which has an infrared emissivity that is higher than that ofthe cover plate.
 4. An apparatus for testing infrared cameras, accordingto claim 1, wherein the cover plate has been subjected to a processingfor reducing infrared reflection.
 5. An apparatus for testing infraredcameras, according to claim 1, wherein the cover plate is verticallymovable in front of the emission source as viewed from the infraredcameras to be tested from a first position at which testing of theinfrared cameras is executed to a second position which is higher thanthe first position.
 6. An apparatus for testing infrared cameras,according to claim 5, wherein the second position is sufficiently higherthan the first position such that the cover plate is not heated by aheat source of the emission source.